What is a difference between "at the point and on the point of?

[XxEMxx]

What is a difference between "at the point and on the point of?
Please help me!

[Mister Micawber]

You'll have to include a specific sentence that bothers you, Xx. Both forms can mean the same thing, and they also collocate differently:

I am at the point of no return.
I am on the point of returning this lemon.
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Native English teacher at Mister Micawber's

[XxEMxx]

I have a sentence:
I was (at the point / on the point of) going out when the telephone rang.

I don't know what these phrases mean and that is why I can't choose what suits the best to this sentence.
If you explain me what is going on i will appreciate:)

[Milanya]

to be at a point - be at a certain place or time
to be on the point of - to be about to do something
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con·text - The part of a text or statement that surrounds a particular word or passage and determines its meaning.

[XxEMxx]

I need help, again.;p
Could you explain me what are the differences between:

How long have you learn English?
How long have you been learning English?

He has slept for ten hours.
He has been sleeping for ten hours.

It has snowed for a long time.
It has been snowing for a long time.

[Mister Micawber]

How long have you learn English?-- No good.
How long have you been learning English?-- OK

He has slept for ten hours.-- He may be awake now
He has been sleeping for ten hours.-- He is still sleeping now

It has snowed for a long time.-- It may be finished now
It has been snowing for a long time.-- It is still snowing now.
_________________
Native English teacher at Mister Micawber's

[Torsten]

[XxEMxx]

I would like to say:
"How I prepared to go to a party."
Is it correct? Or should I change preposition?

[Mister Micawber]

It sounds OK, Xx.
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Native English teacher at Mister Micawber's

[XxEMxx]

May I say: "I was ready to gain the mountains"?

[Mister Micawber]

What do you mean by that?
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Native English teacher at Mister Micawber's

[XxEMxx]

I'd like to say :"to achieve the summit" but I don't know how it says

[Mister Micawber]

Well, I suppose that you could 'gain the summit', but you cannot 'gain the mountain'.
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Native English teacher at Mister Micawber's